Enter a value into either text box and select units using the drop-down boxes. = What is Electrical Conductance? Electrical conductance is a measure of the flow of electricity through an electrical component for a given potential difference. The SI unit of conductance is the siemens. It is the inverse of electrical resistance so that the conductance, G = 1/R, where R is resistance in ohms (hence a playful alternative name for the SI unit is the âmhoâ). Electrical conductance should not be confused with the related measure of conductance, which is a property of the material itself. Conductance is also connected to susceptance and admittance in AC (Alternating Current) circuits. Y= G + jB or G = Re(Y), Where Y= Admittance, j is the imaginary number and B is the Susceptance.

When Kirchhoff's voltage law is applied we find that the voltage is the sum of the voltages across each conductance: G = (G1.G2) / (G1+G2) In semiconductors the conductance of components such as diodes and transistors is usually evaluated for small signal conditions with appropriate bias so that operation is in the linear region of their characteristics. The conductance is therefore the inverse of the small-signal resistance. The electrical conductance is represented by the symbol G. Electrical conductance is a very useful concept when dealing with parallel DC circuits. For this reason, the inverse of impedance is defined as admittance and is similarly useful in parallel AC circuits. Generally when there are resistive and reactive elements then the equation that is formed for G is R/(R2 + X2), where X is reactance. Bookmark this page in your browser using CtrlÂ andÂ d or using one of these services: (opens in new window) What is siemens (mho)? - Definition from WhatIs.com pneumatics (Siemens AG is a German company engaged in electrical engineering and electronics.) The siemens (symbolized S) is the Standard International ( SI ) unit of electrical conductance .

The archaic term for this unit is the mho ( ohm spelled backwards). Siemens are also used, when multiplied by imaginary number s, to denote susceptance in alternating current ( AC ) and radio frequency ( RF ) applications. Reduced to base SI units, 1 S is the equivalent of one second cubed ampere squared per kilogram per meter squared (1 s3 · A2 · kg-1 · m-2). The siemens is also the equivalent of an ampere per volt (A/V). In a direct current (DC) circuit, a component has a conductance of 1 S when a potential difference of one volt (1 V) produces a current of one ampere (1 A) through the component. Thus, one siemens is the equivalent of one ohm. But mathematically, resistance and conductance are reciprocals of each other. If R is the resistance of a component in ohms and G is the conductance in siemens, R = 1 / G and G = 1 / R In AC and RF circuits, conductive siemens behave the same as they do in DC circuits, provided the root-mean-square ( rms ) AC voltage is specified.

In AC and RF circuits, susceptance exists only when there is a net capacitance or inductance. Capacitive susceptances have positive imaginary number values; inductive susceptances have negative imaginary-number values. The susceptance of a particular capacitor or inductor depends on the frequency. Conductances and susceptances are sometimes expressed in units representing power-of-10 multiples or fractions of 1 S. A kilosiemens (1 kS) is equal to one thousand (103) siemens. A megasiemens (1 MS) is equal to one million (106) siemens. A millisiemens (1 mS) is equal to one-thousandth (10-3) of a siemens. A microsiemens (1 uS) is equal to one-millionth (10-6) of a siemens. Also see conductance , Ohm's Law , prefix multiplier s, resistance , reactance , ohm , and Standard International ( SI ) system of units. This was last updated in February 2008 Continue Reading About siemens (mho) Enter a value into either text box and select units using the drop-down boxes. = What is Electrical Conductivity?

Electrical conductivity is a material's ability to conduct an electric current when an electrical potential difference is applied across it. It is also known as specific conductance, and should not be confused with conductance which is a property of a component, whereas conductivity is a property of the substance from which the component is made. The SI unit of electrical conductivity is the siemens per metre (S/m). Conductivity is the inverse of resistivity. The conductivity, σ, is given in terms of current density, J, and electric field strength, E, using the expression: J = σE Materials of high conductivity include metals, especially copper and silver. Silver actually has the highest electrical conductivity but is too expensive for general use for electrical wiring. Copper is the next best choice and is normally used for any type of electrical wiring. Gold is also a good conductor, although not as good as copper and more expensive than silver, but it does have the additional advantage of being corrosion resistant and so is often used as a plating for electrical contacts. Aluminium is often used for overhead power lines because it is a reasonable conductor but has the additional advantage of being light in weight.

At the other extreme, air is an excellent insulator, as are most plastics, ceramics and glass. Air will eventually break down and ionize if there is a sufficient potential difference. Moist air has a higher conductivity and it can often be heard crackling in the vicinity of high-tension power lines when humidity is high. Pure water has a fairly low conductivity, but the presence of ions caused by electrolytes, for example, salts, will greatly increase the conductivity. Measuring the conductivity of water can be used as an indication of salt concentration. Dry materials, such as building materials (wood, brick, plaster) will have low conductivity but this will increase if the materials become damp. The presence of moisture can therefore be detected by measuring its conductivity, and this principle is used in surveyor’s instruments for detecting damp in buildings. The electrical conductivity of the human body can also be measured, and is mostly accounted for by the amount of perspiration in the vicinity of the electrodes. This can be used to detect stress in a lie detector test. Conductivity is measured in the same way as electrical resistance.

Bookmark this page in your browser using CtrlÂ andÂ d or using one of these services: (opens in new window) Electrical Properties Electrical Conductivity and Resistivity It is well known that one of the subatomic particles of an atom is the electron. The electrons carry a negative electrostatic charge and under certain conditions can move from atom to atom. The direction of movement between atoms is random unless a force causes the electrons to move in one direction. This directional movement of electrons due to an electromotive force is what is known as electricity. Electrical Conductivity Electrical conductivity is a measure of how well a material accommodates the movement of an electric charge. It is the ratio of the current density to the electric field strength. Its SI derived unit is the Siemens per meter, but conductivity values are often reported as percent IACS. IACS is an acronym for International Annealed Copper Standard, which was established by the 1913 International Electrochemical Commission. (More Information on the IACS.) The conductivity of the annealed copper (5.8001 x 107S/m) is defined to be 100% IACS at 20Â°C . All other conductivity values are related back to this conductivity of annealed copper.

Therefore, iron with a conductivity value of 1.04 x 107 S/m, has a conductivity of approximately 18% of that of annealed copper and this is reported as 18% IACS. An interesting side note is that commercially pure copper products now often have IACS conductivity values greater than 100% IACS because processing techniques have improved since the adoption of the standard in 1913 and more impurities can now be removed from the metal. Conductivity values in Siemens/meter can be converted to % IACS by multiplying the conductivity value by 1.7241 x10-6. When conductivity values are reported in microSiemens/centimeter, the conductivity value is multiplied by 172.41 to convert to the % IACS value. Electrical conductivity is a very useful property since values are affected by such things as a substances chemical composition and the stress state of crystalline structures. Therefore, electrical conductivity information can be used for measuring the purity of water, sorting materials, checking for proper heat treatment of metals, and inspecting for heat damage in some materials. Electrical Resistivity Electrical resistivity is the reciprocal of conductivity.

It is the is the opposition of a body or substance to the flow of electrical current through it, resulting in a change of electrical energy into heat, light, or other forms of energy. The amount of resistance depends on the type of material. Materials with low resistivity are good conductors of electricity and materials with high resistivity are good insulators. The SI unit for electrical resistivity is the ohm meter. Resistivity values are more commonly reported in micro ohm centimeters units. As mentioned above resistivity values are simply the reciprocal of conductivity so conversion between the two is straightforward. For example, a material with two micro ohm centimeter of resistivity will have Â½ microSiemens/centimeter of conductivity. Resistivity values in microhm centimeters units can be converted to % IACS conductivity values with the following formula: 172.41 / resistivity = % IACS Temperature Coefficient of Resistivity As noted above, electrical conductivity values (and resistivity values) are typically reported at 20 oC. This is done because the conductivity and resistivity of material is temperature dependant. The conductivity of most materials decreases as temperature increases. Alternately, the resistivity of most material increases with increasing temperature.

The amount of change is material dependant but has been established for many elements and engineering materials. The reason that resistivity increases with increasing temperature is that the number of imperfection in the atomic lattice structure increases with temperature and this hampers electron movement. These imperfections include dislocations, vacancies, interstitial defects and impurity atoms. Additionally, above absolute zero, even the lattice atoms participate in the interference of directional electron movement as they are not always found at their ideal lattice sites. Thermal energy causes the atoms to vibrate about their equilibrium positions. At any moment in time many individual lattice atoms will be away from their perfect lattice sites and this interferes with electron movement. When the temperature coefficient is known, an adjusted resistivity value can be computed using the following formula: R1 = R2 * [1 + a * (T1–T2)] Where: R1 = resistivity value adjusted to T1 R2 = resistivity value known or measured at temperature T2 a = Temperature Coefficient T1 = Temperature at which resistivity value needs to be known T2 = Temperature at which known or measured value was obtained For example, suppose that resistivity measurements were being made on a hot piece of aluminum.

Normally when measuring resistivity or conductivity, the instrument is calibrated using standards that are at the same temperature as the material being measured, and then no correction for temperature will be required. However, if the calibration standard and the test material are at different temperatures, a correction to the measured value must be made. Presume that the instrument was calibrated at 20oC (68oF) but the measurement was made at 25oC (77oF) and the resistivity value obtained was 2.706 x 10-8 ohm meters. Using the above equation and the following temperature coefficient value, the resistivity value corrected for temperature can be calculated. R1 = R2 * [1 + a * (T1–T2)] Where: R1 = ?

R2 = 2.706 x 10-8 ohm meters (measured resistivity at 25 oC) a = 0.0043/ oC R1 = 2.706 x 10-8ohm meters * [1 + 0.0043/ oC * (20 oC – 25 oC)] R1 = 2.648 x 10-8ohm meters Note that the resistivity value was adjusted downward since this example involved calculating the resistivity for a lower temperature. Since conductivity is simply the inverse of resistivity, the temperature coefficient is the same for conductivity and the equation requires only slight modification.

The equation becomes: s1 = s2 / [1 + a * (T1–T2)] Where: s1 = conductivity value adjusted to T1 s2 = conductivity value known or measured at temperature T2 a = Temperature Coefficient T1 = Temperature at which conductivity value needs to be known T2 = Temperature at which known or measured value was obtained In this example let’s consider the same aluminum alloy with a temperature coefficient of 0.0043 per degree centigrade and a conductivity of 63.6% IACS at 25 oC. What will the conductivity be when adjusted to 20 oC? s1= 63.6% IACS / [1 + 0.0043 * (20 oC – 25 oC)] s1= 65.0% IASC The temperature coefficient for a few metallic elements is shown below. Material Online Unit Converters • Electrical Engineering • Electrical Conductivity • Compact Calculator Experiment: Measuring TDS and Conductivity Introduction and Definition Electrical conductivity or specific conductance is a measure of the ability of a substance to conduct electric current or to transport an electric charge.

It is the ratio of the current density to the strength of the electric field. If we consider a 1-meter cube of a conductive material, then the conductivity will be equal to the electrical conductance measured between the opposite faces of this cube. The conductivity and conductance are related by the formula: G = σ(A/l) where G is the conductance, σ is the conductivity, A is the cross-sectional area of the conductor, which is perpendicular to the direction of flow of an electric current, and l is the length of the conductor. This formula can be used with any cylindrical or prismic conductor. Note that this formula can be also used for a cuboid because it is a rectangular prism. Electrical conductivity is the reciprocal of electrical resistivity. In the English language words conductance and conductivity are so similar that they are often used as synonyms. Meanwhile, they have different meaning, of course. The conductance is the extrinsic property of a given conductor or device (for example, a resistor or a galvanic bath) and the conductivity is an intrinsic property of the material from which this conductor or device were made.

For example, the conductivity of copper is always the same, no matter how the object made from copper changes in terms of its shape or size, while the conductance of a copper wire depends on its length, diameter, mass, shape, and several other factors. Of course, similar objects made from materials with higher conductivity will have a higher conductance (not always). The conductivity of copper is always the same no matter how the object made from copper changes in terms of its shape or size The SI unit for electrical conductivity is siemens per meter (S/m). Note that in English, the same form of the unit of conductance "siemens" is used both for the singular and plural forms. The unit is named after the German inventor, industrialist and scientist Werner von Siemens (1816–1892). Siemens AG, the company he founded in 1847, is one of the largest engineering companies in the world producing electrical, electronic as well as transport and medical equipment.

Left: Werner von Siemens (source: Wikipedia); right: Siemens Canada Limited Headquarters in Oakville, Ontario, Canada Electrical conductivity ranges from highly resistive materials like glass (which, by the way, conducts electricity well when heated) or acrylic glass to semiconductors, which have a different conductivity under different conditions to extremely conductive materials like silver, copper or gold. The electrical conductivity is determined by the number of charge carriers such as electrons or ions, by the speed of their movement and by the amount of charge they carry. Conductivity of aqueous solutions, for example, electroplating baths, is between these extremes. Another example of electrolytes with moderate conductivity are our bodily fluids: blood, plasma, lymph, etc. The conductivity of metals, semiconductors and dielectrics is discussed in detail in More about Electrical Resistance , More about Electrical Resistivity and Electrical Conductance and Conductivity TranslatorsCafe.com Unit Converter articles. In this article we will discuss in more details the conductivity of electrolytes and its measuring methods and equipment. We will describe several experiments using an inexpensive device for measuring conductivity.

Electrolytic Conductivity and Its Measuring Our body fluids — blood, lymph and interstitial fluid — are all have a high concentration of sodium chloride and other minerals; they are all electrolytes; the conductivity of blood is approximately 0.54 S/m at 37°C The conductivity of aqueous solutions, in which the electric current is carried by charged ions, is determined by the number of charge carriers (the concentration), the speed of their moving (the ion mobility depends on the solution temperature) and the charge they carry (valence of ions). Therefore, in most aqueous solutions, the higher concentration will lead to more ions and hence to higher conductivity. However, after reaching some maximum concentration, the conductivity may start decreasing with increasing concentration. Therefore, two different concentrations of the same salt may have the same conductivity. The temperature also affects conductivity because at higher temperatures ions move faster, increasing the conductivity. Pure water does not conduct electricity well. The ordinary distilled water in equilibrium with carbon dioxide containing in the air and total dissolved solids of less than 10 mg/L has a conductivity of about 20 µS/cm. The conductivity of various solutions is given in the table below.

Conductivity of distilled water is approximately 0.055 μS/cm Conductivity of various water solutions at 25°C Pure water Hydrochloric acid, 1 mol/L 332 mS/cm Two electrodes of a conductivity sensor (left) and the temperature sensor (right) used for automatic temperature compensation (ATC) in a TDS meter To determine the conductivity of a solution, a conductance or resistance meter (they are technically the same) is usually used and the measured value is then manually or automatically recalculated to conductivity. This is done by taking into account the physical characteristics of the measuring device or sensor. This includes the area of electrodes and the separation distance between the two electrodes. The sensors are quite simple: they comprise a pair of electrodes immersed into the electrolyte solution. The sensors for measuring conductivity are characterised by a cell constant, which is given by the ratio of the distance between electrodes D to the area normal to the current flow A: K = D/A This formula works well when the area of electrodes is much greater than the separation between them because in this case most of the electric current flows directly between the electrodes.

Example: for 1 cubic centimeter of liquid K = D/A = 1 cm/1 cm² = 1 cm⁻¹. Note that cells with small widely-spaced electrodes have cell constants of 1.0 cm⁻¹ or more while cells with larger and closely-spaced electrodes have constants of 0.1 cm⁻¹ or less. The cell constant of various devices for measuring conductivity varies from 0.01 to 100 cm⁻¹. Theoretical cell constant: left — K = 0.01 cm⁻¹ , right — K = 1 cm⁻¹ To obtain the conductivity from the measured conductance, the following formula is used: σ = K ∙ G σ is the solution conductivity in S/cm, K is the cell constant in cm⁻¹, G is the cell conductance in siemens. The cell constant is usually not calculated, but measured for a particular measuring device or setup using a solution of known conductivity. This measured value is entered into the meter, which automatically calculates the conductivity from measured conductance or resistance.

Because the conductivity depends on the solution temperature, devices for measuring conductivity often contain a temperature sensor that allows measuring the temperature and providing the automatic temperature compensation (ATC) to the standard temperature of 25°C. The simplest method of measuring the conductance is applying a voltage to two flat electrodes immersed in the solution and measuring the resulting current. This is called a potentiometric method. According to Ohm’s law, the conductance G is the ratio of current I to voltage V: G = I/V However, things are not as simple as they seem. There are many difficulties. When DC voltage is used, ions can accumulate near the electrode surfaces and chemical reactions can occur at the surfaces. This will lead to increasing polarization resistance on the electrode surfaces, which, in turn, may lead to erroneous results. If we try to measure the resistance of, for example, sodium chloride solution using a multimeter, we will clearly see that the reading on the display is increasing rather quickly. To mitigate this problem, often four electrodes are used instead of two. Electrode polarisation can be prevented or reduced by applying an alternating current and adjusting the measuring frequency. Low frequencies are used to measure low conductivity, where the polarization resistance is comparatively small.

Higher frequencies are used to measure high conductivity values. Frequency is usually automatically adjusted taking into account the measured conductivity of a solution. Modern digital 2-electrode conductivity meters usually use complex alternating current waveforms and temperature compensation. They are calibrated at the factory and often recalibration is required in the field because the cell constant changes with time. It can be changed due to contamination or physical-chemical modification of electrodes. In a traditional 2-electrode conductivity meter, an alternating voltage is applied between the two electrodes and the resulting current is measured. This meter, though simple, has one disadvantage — it measures not only the solution resistance, but also the resistance cause by polarisation of the electrodes. To minimize the effect of polarization, 4-electrode cells as well as platinised cells covered with platinum black are often used. Total Dissolved Solids (TDS) Devices for measuring electrical conductivity are often used to measure total dissolved solids (TDS). It is a measure of the total weight of all organic and inorganic substances contained in a liquid in various forms: ionized, molecular (dissolved), colloidal and suspended (not dissolved).

Dissolved solids refer to any inorganic salts, mostly calcium, potassium, magnesium, sodium, chlorides, bicarbonates and sulfates, and some organic matter dissolved in water. The solid substances contained in a liquid, which is considered for TDS, must be either dissolved or in the form of very small particles that will remain the solution after filtration through a filter with very small pores (2 micrometer or less). Substances that are permanently suspended in a solution, but cannot pass through a filter are called total suspended solids or TSS. Total dissolved solids are usually measured in water to determine its quality. Filter operating gallery of R.C. Harris Water Treatment Plant in Toronto, Ontario, Canada There are two main methods of measuring total dissolved solids: gravimetric analysis, which is the most accurate method, and conductivity measurement. The first method is the most accurate, but it is time-consuming because all water must be evaporated, to dryness, usually at 180°C under strict laboratory conditions and then the mass of residues is measured. The second method is not as accurate as the gravimetric analysis.

However, the conductivity method is the most convenient, useful, widespread and fastest method because it is simple measurement of conductivity and temperature, which can be done in seconds by means of a low-cost device. This method can be used because electrical conductivity of water is directly related to the concentration of ionised substances dissolved in water. It is especially useful for quality control purposes like control of drinking water or estimation of the total number of ions in a solution. The conductivity measurements are temperature dependent, that is, if the temperature increases, the conductivity also increases because the ions in a solution are moving faster. To obtain temperature-independent measurements, the concept of reference temperature was introduced. It allows comparison of conductivity results obtained at different temperatures. Thus, the conductivity meter can measure the actual conductivity and the temperature and then use a temperature correction function to automatically convert the measured value to the reference temperature of 20 or 25°С. If very high accuracy is necessary, the sample can be put into a thermostat and then the meter will be calibrated at exactly the same temperature that is used for measurement. Most modern conductivity meters contain a built-in temperature sensor that can be used for temperature correction as well as for temperature measurement.

The most sophisticated meters can measure and display conductivity, resistivity, salinity, TDS and concentration. However, all of them measure only conductivity and temperature and then calculate the necessary physical value and make temperature compensation. Experiment: Measuring TDS and Conductivity We will conduct several experiments using an inexpensive TDS meter TDS-3. The price on eBay with delivery at the time of writing this article for a no-name device is less than US$3.00. The same device with a brand name probably made at same factory will costs 10 times more. But that’s for those who like to pay just for the brand name. The meter is temperature calibrated and can measure not only TDS, but also a temperature using the temperature sensor, which is installed near the electrodes. It should be noted that the two actual physical values that this device measures are the resistance of the solution between the two electrodes and the temperature of the solution.

TDS-3 Meter; the two electrodes and a temperature sensor of the meter are shown on the left This TDS meter will help you find out the total dissolved solids in any application such as monitoring the quality of drinking water or testing salt levels in freshwater aquariums and ponds or testing water filtration and purification system to know when to change filters and membranes. The meter is calibrated using 342 ppm solution of sodium chloride NaCl. Its range is 0–9990 ppm or mg/L. PPM is parts per million. It is a dimensionless quantity. For example, a mass concentration of 5 mg/kg = 5 mg in 1,000,000 mg = 5 parts per million. Just as a percent means out of hundred, parts per million means out of a million. Therefore, PPM is a way of measuring concentration of very dilute solutions. The meter actually measures the conductance between the two electrodes (which is reciprocal of resistance), then recalculates the result into electrical conductivity (often abbreviated as EC) using the formula above and the known cell constant K, then makes another recalculation, multiplying the conductance by the conversion factor of 500.

The result of these calculations is displayed in the form of TDS in ppm. We will discuss these calculations below. Waveform of the signal on the dry electrodes of TDS-3 meter; frequency 20 Hz, peak-to-peak amplitude 4.4 V; alternating current reduces electrode polarisation This TDS meter cannot be used to test water with high concentration of salts. Examples of substances with a high concentration of salts are some food products and seawater. The maximum concentration of NaCl the device can measure is 9990 ppm or about 10 g/L. That is only the normal concentration of salt in many food products. This meter will also not be able to check the salinity of seawater, which is approximately 35 grams per liter or 35,000 ppm, which is much higher than this device can measure. If you try to measure the TDS of such concentrated electrolyte, the meter will show Err. TDS-3 measures conductivity and uses the 500 (NaCl) scale for calibration. That means 1.0 mS/cm x 500 = 500 ppm. There are many different scales in many industries.

For example, three scales are usually used in hydroponics: the 500, 640 and 700 scales. The difference between them is in their use. The 700 scale is based on measuring the potassium chloride KCl concentration in a solution: 1.0 mS/cm x 700 makes 700 ppm The 640 scale uses conversion factor of 640 to convert from mS/cm to ppm: 1.0 mS/cm x 640 makes 640 ppm For our experiment, we will first measure the total dissolved solids in distilled water. The meter shows 0 ppm and the multimeter shows 1.21 MΩ. Measuring concentration of dissolved solids in distilled water (0 ppm) and resistance between the two electrodes in distilled water (1.21 MΩ) Let us prepare a 1000 ppm solution of NaCl and measure its ppm with TDS-3 meter. To prepare 100 mL of the solution, we will need 100 mg of sodium chloride and up to 100 mL of distilled water.

To make a solution, we will put the sodium chloride into the measuring cylinder, add some distilled water and stir it until all sodium chloride is dissolved. Then add distilled water to 100 mL mark and mix well again. Left to right: weighing 100 mg of NaCl; 100 mL of NaCl solution; measuring concentration using TDS-3 meter As you can see in the picture, TDS-3 measures 955 ppm. The conductivity of this solution should be 1000 ppm / 500 = 2 mS/cm (NaCl or 500 scale). Measuring resistance between the two electrodes made of the same material and with the same dimensions as TDS-3 electrodes; the multimeter shows 2.5 kΩ To determine the conductance experimentally, we measured the resistance between the two electrodes made from the same material, with size and distance between them as in TDS-3. The measured resistance was 2.5 kΩ.

Now, when we know the resistance and ppm, we can approximately calculate the cell constant of TDS-3 using the formula above: K = σ/G = 2 mS/cm x 2.5 kΩ = 5 cm⁻¹ Dimensions of the two electrodes of TDS-3 meter This value of 5 cm⁻¹ is close to the calculated value of the cell constant of TDS-3 with the following electrode dimensions: D = 0.5 cm is the distance between the electrodes W = 0.14 cm is the electrode width L = 1.1 cm is the length of the electrode Cell constant of TDS-3 cell is K = D/A = 0.5/0.14x1.1 = 3.25 cm⁻¹. This is slightly less than the value of 5 cm⁻¹. Note that the formula for calculating the cell constant can give only approximate value. This article was written by Anatoly Zolotkov You can hide articles if you use this converter often. Cookies must be allowed in your browser. You may be interested in another converters in the Electrical Engineering group: Learn Technical English with Our Videos!

You can use this online converter to convert between several hundred units (including metric, British and American) in 76 categories, or several thousand pairs including acceleration, area, electrical, energy, force, length, light, mass, mass flow, density, specific volume, power, pressure, stress, temperature, time, torque, velocity, viscosity, volume and capacity, volume flow, and more. Note: Integers (numbers without a decimal period or exponent notation) are considered accurate up to 15 digits and the maximum number of digits after the decimal point is 10. In this calculator, E notation is used to represent numbers that are too small or too large. E notation is an alternative format of the scientific notation a · 10x. For example: 1,103,000 = 1.103 · 106 = 1.103E+6. Here E (from exponent) represents “· 10^”, that is “times ten raised to the power of”. E-notation is commonly used in calculators and by scientists, mathematicians and engineers. Select the unit to convert from in the left box containing the list of units.

Select the unit to convert to in the right box containing the list of units. Enter the value (for example “15”) into the left From box. The result will appear in the Result box and in the To box. Alternatively, you can enter the value into the right To box and read the result of conversion in the From and Result boxes. If you have noticed an error in the text or calculations, or you need another converter, which you did not find here, please let us know ! ELECTROCHEMISTRY | INTRODUCTION | SPECIFIC & EQUIVALENT CONDUCTANCE Electrochemistry deals with the study of electrochemical processes and their applications which involve: i) the conversion of electrical energy into chemical energy and ii) the conversion of chemical energy into electrical energy. It is possible to carry out a non spontaneous chemical reaction by applying sufficient electrical voltage in an electrochemical cell. In this case, the electrical energy is converted to chemical energy. E.g. Preparation of sodium metal by Down's process. It is also possible to produce electrical energy by carrying out a spontaneous chemical reaction in a suitable device called galvanic cell or voltaic cell. E.g. Batteries and fuel cells. Electrochemistry is an interdisciplinary subject.

Its scope and practical applications covers several fields of science including metallurgical processes, biological sciences, analytical techniques, space research, energy systems etc. BASIC CONCEPTS AND TERMINOLOGY Electricity: The term electricity refers to a form of energy or variety of phenomenon resulting from the accumulation of static charges or flow of charged particles. Electric charge: The electric charge is the fundamental and conserved property of some subatomic particles which determines their electromagnetic interactions. It exhibits two states i.e., positive and negative. In SI units, the electric charge is measured in Coulombs (C). The smallest value of “free” charge known in nature is the charge of an electron or a proton, which has a magnitude of 1.602 x 10-19 Coulomb. The charge on one electron is: -1.602 x 10-19 C. Whereas the charge on a proton is equal to: +1.602 x 10-19 C. Electric field: It is an influence produced by an electric charge on other charges in its vicinity. A charged particle experiences force when placed in an electric field.

The electric field exerts a force on charged particles, accelerating them in the direction of the force, in either the same or the opposite direction of the electric field. Hence some amount of work has to be done against this force to bring the charged particle to a certain point in an electric field. Electric potential: The electric potential at any point in an electric field is defined as the energy required to bring a unit charge from an infinite distance to that point. It is usually measured in volts (V). Volt can be formally defined as the ratio of energy in joules to the charge in coulombs. The absolute electric potential cannot be measured. However, the difference in electric potential between two points can be measured and has more practical usage. Electric potential difference or voltage: It is the energy required to move a unit charge between two specified points in an electric field. However, it is usually referred to as electric potential or some times as voltage. One Volt (V) is equal to 1 Joule per 1 Coulomb. Electromotive force (emf): Formally it is same as electric potential difference. It is the potential energy divided by electric charge and is measured in volts.

It can be defined as the external work expended per unit of charge to produce an electric potential difference thereby causing the current to flow in the circuit. Note: Though there are several different definitions given across the literature, the above explanation is sufficient in electrochemistry. Current: Formally it is the flow of charged particles like electrons, protons, ions. The strength of current (I) is defined as the charge transferred in unit time. It is measured in amperes (A). One ampere (A) is defined as 1 coulomb of electricity transferred in one second. ELECTRICAL RESISTANCE & CONDUCTANCE Resistance (R): The tendency of a material to stop the flow of current is known as resistance. It is measured in ohms (Ω). According to Ohm's law, the resistance offered by a substance is directly proportional to its length (l), but inversely proportional to its cross sectional area (A). In case of electrolytic solutions, 'l' represents the distance between two electrodes and the 'A' is the cross sectional area of the electrodes. The above equation can also be written as: -------- equation (1) Where ρ is the proportionality constant and is known as specific resistance or resistivity.

If A = 1 cm2 and l = 1 cm, then R = ρ. Therefore, the specific resistance can be defined as follows: Specific resistance or resistivity (ρ): It is the resistance offered by a material or solution occupying one cm3 volume. It is measured in: ohm. cm (in C.G.S system) or ohm. m (in S.I system) Its unit can be derived as follows: Conductance (G): It is the tendency of a material to allow the flow of current through it. It is the reciprocal of resistance. It is measured in ohm-1 = mho = Siemens. By substituting, R from equation (1): ---------- equation (2) If A = 1 cm2 and l = 1 cm, then κ = G. Therefore the specific conductance can be defined as: specific conductance or conductivity (κ): It is the conductance of a material or solution occupying one cm3 volume. It is measured in: ohm-1. cm-1 = mho. cm-1 (C.G.S system) or Siemens. m-1 (S.I system) * The specific conductance depends on the nature of substance or the electrolyte.

* It increases with increase in concentration of the electrolytic solution since the number of ions per unit area increases. Cell constant (G*): The ratio of the distance between the electrodes, l to the cross sectional area, A of the electrodes is known as cell constant. The cell constant can be determined by using following relations which can be derived easily from expressions discussed above. TYPES OF SUBSTANCES BASED ON ELECTRICAL CONDUCTANCE Based on electrical conductivity, the materials are divided into two types as follows: 1) Insulators: The substances which resist the flow of electric current through them are called insulators. They do not have free electrons or freely moving charged particles. E.g. Organic polymers (like plastics), glass, diamond, quartz etc., 2) Conductors: The substances which allow the flow of electricity through them with little resistance are known as conductors. They are again divided into: i) Metallic or electronic conductors: The conductors which conduct the electricity through the electrons. E.g. All metals, Graphite etc. In case of metallic conductors; * No chemical reaction occurs during the conduction of electricity. * Conductivity decreases with increase in temperature due to vibrational disturbances.

ii) Electrolytes: The substances which furnish oppositely charged ions for the conduction of electricity. E.g :- NaCl, KCl, CH3COOH, HCl etc. In case of electrolytes; * There is flow of ions towards the oppositely charged electrodes. * During conduction of electricity through electrolytes, oxidation occurs at anode whereas reduction occurs at cathode i.e., a chemical reaction occurs. * The conductivity increases with increase in temperature as the extent of ionization increases. The electrolytes undergo dissociation to furnish ions either in molten state or in aqueous solutions. Depending on the extent of ionization (or dissociation) in water, the electrolytes are further divided into: a) Strong electrolytes: Undergo complete ionization in water. E.g. NaCl, KCl, K2SO4, HCl, H2SO4,NaOH, NaNO3 etc. b) Weak electrolytes: Under go partial ionization in water. E.g. HF, CH3COOH, NH4OH, HCOOH etc. Non-electrolytes: The substances which do not furnish ions for electrical conduction are called non-electrolytes.

E.g : urea, glucose, sucrose etc. EQUIVALENT CONDUCTANCE & MOLAR CONDUCTANCE Equivalent conductivity (Λ): The conductance of that volume of solution containing one equivalent of an electrolyte is known as equivalent conductivity. It is denoted by Λ. Let us consider the V cm3 of solution containing one equivalent of an electrolyte. Its conductance is equal to equivalent conductance, Λ. Also we know that the conductance shown by 1 cm3 solution containing this electrolyte is called specific conductance, κ. i.e., the conductance of V cm3 --------- Λ the conductance of 1 cm3 --------- κ Therefore: We know that the normality (N) of a solution is given by the equation: For above electrolytic solution, no. of equivalents, ne = 1. Hence By substituting the above value in the equation (3), we can now write: Units of Λ: = cm2 . ohm-1. equiv-1 = cm2 . mho. equiv-1 or m2 . Siemens.

equiv-1 Molar conductivity (Λm or μ): The conductance of that volume of solution containing one mole of an electrolyte is known as molar conductivity. It is denoted by Λm or μ. It is related to specific conductance, κ as: μ = κ.V The relation between equivalent conductance, Λ and molar conductance, μ can be given by: μ = Λ x equivalent factor of the electrolyte The equivalent factor of the electrolyte is usually the total charge on either anions or cations present in one formula unit of it. It may be equal to basicity in case of acids or equal to acidity in case of bases. Temperature: The conductance of an electrolyte solution increases with increase in the temperature due to increase in the extent of inonization. Nature of electrolyte: * The strong electrolytes undergo complete ionization and hence show higher conductivities since they furnish more number of ions. * Whereas weak electrolytes undergo partial ionization and hence show comparatively low conductivities in their solutions. Ionic size & mobility: * The ionic mobility decreases with increase in its size and hence conductivity also decreases. E.g.

In molten state, the conductivities of lithium salts are greater than those of cesium salts since the size of Li+ ion is smaller than that of Cs+ ion. * However, in aqueous solutions the extent of hydration affects the mobility of the ion, which in turn affect the conductivity. Heavily hydrated ions show low conductance values due to larger size. E.g. In aqueous solutions Li+ ion with high charge density is heavily hydrated than Cs+ ion with low charge density. Hence hydrated Li+ bigger than hydrated Cs+ . As a result, lithium salts show lower conductivities compared to those of cesium salts in water. The nature of solvent and its viscosity: * The ionic mobility is reduced in more viscous solvents. Hence the conductivity decreases. Concentration: * The specific conductance (κ) increases with increase in concentration of solution as the number of ions per unit volume increases. * Whereas, both the equivalent conductivity and molar conductance increase with decrease in concentration (i.e. upon dilution) since the extent of ionization increases. Explanation: Since the concentration decreases, one can expect decrease in equivalent conductivity due to decrease in available number of ions per unit volume.

However the increase in volume (V) factor more than compensates this effect. The volume must be increased in order to get one equivalent of electrolyte since the concentration is decreased. Hence the net effect is increase in equivalent conductivity. Limiting equivalent conductivity (Λo): The equivalent conductivity reaches a maximum value at certain dilution and does not change upon further dilution (i.e., by adding solvent further). This concentration is also termed as infinite dilution. The equivalent conductivity at infinite dilution is known as the limiting equivalent conductivity (Λo). At this dilution, the ionization of even the weak electrolyte is complete. However at infinite dilution (i.e., when concentration approaches zero) the conductivity of the solution is so low that it cannot be measured accurately. Therefore the limiting equivalent conductivity of an electrolyte is calculated by using Debye-Huckel-Onsagar equation as explained below. Conductance ratio (α) : The ratio of the equivalent conductance at given concentration, Λc to that at infinite dilution, Λo is called conductance ratio, α. For weak electrolytes, the 'α' is also called as degree of ionization.

It is possible to determine the equivalent conductivities of electrolytes in water at given concentration by using Debye-Huckel-Onsagar equation. Where Λc= equivalent conductivity at given concentration. Λo= equivalent conductivity at infinite dilution. c = concentration D = Dipole moment of water T = Absolute temperature A straight line with negative slope is obtained when the equivalent conductivity values (Λc) of strong electrolytes are plotted against square roots of different concentrations (√c). The equivalent conductivity at infinite dilution (Λo) can be determined by extending this straight line to zero concentration. However the equivalent conductivity of weak electrolytes increases steeply at very low concentrations (see the above graph) and hence their limiting values (Λo) cannot be determined by extrapolating the Λc to zero concentration. Therefore, Λo for weak electrolytes is obtained by using Kohlrausch law of independent migration of ions , which is described in the next section. What is Conductance? - Definition from Corrosionpedia Conductance Definition - What does Conductance mean? Conductance serves as the measure of how efficiently electricity travels along a particular pathway via an electrical component. It is measured by the SI unit siemens.

However, this should not be mistaken for conduction, the charge flow mechanism or the conductivity of materials. It is best to think of it as the ease with which electric currents flows throughout a particular matter. Awesome Webinar -- You gotta sign up now!!! Corrosionpedia explains Conductance By definition, resistance refers the degree of friction, carries the symbol "R" and is measured in ohms. Conductance, is the opposite of resistance. It is easier to understand electrical properties if it is viewed as how easily the electrons pass through components rather than the other way around. If resistance is used to represent how the electrons flow, a more suitable word to express the ease of the flow of electron is conductance. In mathematical terms, conductance is actually the inverse or reciprocal of resistance. With this, the higher the resistance, the lesser the degree of conductance. With this idea, a symbol was derived for conductance, "G," and is measured in siemens (S). Conductance is vital in the monitoring of parallel circuits and electrical flow. It is also beneficial in the petrochemical industry. For instance, petroleum permeability against spongy rock can be interpreted by means of a conductance graph.

When weights are on the edges and extra weights are added, the reciprocal weights are summed up if the weight is in resistance form. Share this:

Question: What is the SI unit of electrical conductance?
Answer: SIEMENS